Strain-insulator.



UNITED STATES PATENT OFFICE.

ALBERT ANDERSON, OF BOSTO, MASSACHUSETTS, ASSIGNOR TO ALBERT AND I. .-lNDllf L SON MUFACTURTNG COMPANY, OF BOSTON,MASSACHUSETTS, A CORPORATlON MAINE.

STRAIN-INSULATOR.

no. seenoa..

Specification of Letters Patent.

Patented Oct. 29, 1907.

Application filed July 5. 1906. Serial No. 324,783.

`letters on the drawings representing like parts.

The invention relates to an electric insulator or" that class known as strain insulators, such as commonly employed in the overhead electric railway syst-ems, and is an improvement upon the strain insulator shown and described in another application, Serial No. 303,756 filed by me March 2, 1906.

-The present invention has for it-s object to provide a strain 'insulator which is capable of withstanding a severe or great strain and can be produced at a minimum cost, thereby enabling it to be extensively used. These and other features othis invention will be pointed out in the claims at the end of this specification. v

. Figure l is an elevation of a strain insulator embodying lthis invention, and Fig. 2, a longitudinal section with parts in elevation of the insulator shown in Fig. 1.

The strain insulator herein shown as embodying this invention comprises a metallic shell a spherical in shape and provided with an opening b for the passage of the shank c of a member shown as an eye bolt which is provided at one end with an eye d and at its other end with. ahead e, which latter is preferably provided with a curved surface adjacent to the inner curved surfaceof the shell which surrounds the opening b. The metallic shell a has attached to or forming part of it a shank f having as shown an eye g, which shank is located substantially opposite to the opening b.

The shell o is electrically separated from the eye bolt by insulating material h of any suitable material, and said shell is also enveloped by a covering i of insulating material.

in practice, the shell a is made in the form of a cylinder closed at one end and open at the other, the

closed end having attached to it the shank f. The insulating material `h in plastic orm or other condition capable ol 'being molded is placed within the cylindrical shell, and the head e of the eye bolt or member I is then centered within the shell, which is compressed in suitable dies or molds to substantially close the open end oi' the cylinder', 'that is to contract the same so as to form the opening b, at the same time imparting to the shell a substantially spherical. forni 'which is of substantially the same curvature on its inner surface as the curve' oi the head r1, thereby increasing the ability of the insulator' to withstand severe strains. The in'- sulating material for the cover i is subsequently applied. By attaching 'the shank f to the shell a, these parts may be cast in one piece and the cost materially reduced thereby, thus enabling substantially inexpensive strain insulators to be made which are capable of withstanding a severe or great strain.

Claims.

1. In an insulator of the class described, incombination, a metallic shell having a shank attached to it und provided with n substantially dametrlcally opposite openlng and with a substantially spherical curvedinnel' surface ad jacent to said opening, a metallic member extendedthrough said opening andhaving within the saldshell a head, and insulating,` material within the shell separating said head from said shell. substantially as described.

l2. ln an insulator' of the class described, 1in combination,

-a substantially spherical metallic shell having a shank in suluting material enveloping said shell and the portion of the metallic member within the same, substantially as described.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses,

ALBERT ANDERSON. Witnesses das. I-I. CnUncnrLL,

J. MURPHY. 

